[PATCH v3 1/6] media: v4l2-dev: Add range check for vdev->minor

[Ricardo Ribalda]

If the fixed minor ranges are not properly set we could end up in a
situation where the calculated minor is invalid. Add a check for this in
the code to make it more robust.

This check also fixes the following false positive smatch warning:

drivers/media/v4l2-core/v4l2-dev.c:1036 __video_register_device() error: buffer overflow 'video_devices' 256 <= 288
drivers/media/v4l2-core/v4l2-dev.c:1043 __video_register_device() error: buffer overflow 'video_devices' 256 <= 288
drivers/media/v4l2-core/v4l2-dev.c:1101 __video_register_device() error: buffer overflow 'video_devices' 256 <= 288

Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
---
 drivers/media/v4l2-core/v4l2-dev.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
index 6ce623a1245a..5516b2bbb08f 100644
--- a/drivers/media/v4l2-core/v4l2-dev.c
+++ b/drivers/media/v4l2-core/v4l2-dev.c
@@ -1032,6 +1032,11 @@ int __video_register_device(struct video_device *vdev,
 	vdev->minor = i + minor_offset;
 	vdev->num = nr;
 
+	if (WARN_ON(vdev->minor >= VIDEO_NUM_DEVICES)) {
+		mutex_unlock(&videodev_lock);
+		return -EINVAL;
+	}
+
 	/* Should not happen since we thought this minor was free */
 	if (WARN_ON(video_devices[vdev->minor])) {
 		mutex_unlock(&videodev_lock);

-- 
2.54.0.545.g6539524ca2-goog